fix(psd): handle indexed transparency index zero

Signed-off-by: Vlad (Kuzmin) Erium <libalias@gmail.com>

Author: ssh4net

src/psd.imageio/psdinput.cpp

@@ -214,6 +214,7 @@ class PSDInput final : public ImageInput {
     std::vector<std::string> m_alpha_names;
     //Index of the transparent color, if any (for Indexed color mode only)
     int16_t m_transparency_index;
+    bool m_has_transparency_index;
     //Background color
     float m_background_color[4];
     ///< Do not convert unassociated alpha
@@ -912,6 +913,7 @@ PSDInput::init()
     m_channels.clear();
     m_alpha_names.clear();
     m_transparency_index      = -1;
+    m_has_transparency_index  = false;
     m_keep_unassociated_alpha = false;
     m_background_color[0]     = 1.0;
     m_background_color[1]     = 1.0;
@@ -1262,15 +1264,23 @@ PSDInput::load_resource_1039(uint32_t length)
 
 
 bool
-PSDInput::load_resource_1047(uint32_t /*length*/)
+PSDInput::load_resource_1047(uint32_t length)
 {
+    if (length != sizeof(m_transparency_index)) {
+        errorfmt("[Image Resource] Transparency index length {} is invalid",
+                 length);
+        return false;
+    }
+
     if (!read_bige<int16_t>(m_transparency_index))
         return false;
-    if (m_transparency_index < 0 || m_transparency_index >= 768) {
+    if (m_transparency_index < 0 || m_transparency_index >= 256) {
         errorfmt("[Image Resource] Transparency index {} is out of range",
                  m_transparency_index);
         return false;
     }
+
+    m_has_transparency_index = true;
     return true;
 }
 
@@ -1980,7 +1990,7 @@ PSDInput::setup()
             spec_channel_count++;
             raw_channel_count++;
         } else if (m_header.color_mode == ColorMode_Indexed
-                   && m_transparency_index) {
+                   && m_has_transparency_index) {
             spec_channel_count++;
         }
     }
@@ -2144,7 +2154,11 @@ PSDInput::indexed_to_rgb(span<unsigned char> dst, cspan<unsigned char> src,
     OIIO_ASSERT(src.size() && dst.size());
     // The color table is 768 bytes which is 256 * 3 channels (always RGB)
     const auto& table(m_color_data.data);
-    if (m_transparency_index >= 0) {
+    if (src.size() < span_size_t(width))
+        return false;
+    if (m_has_transparency_index) {
+        if (dst.size() < span_size_t(width) * 4)
+            return false;
         for (int i = 0; i < width; ++i) {
             int index = src[i];
             if (index == m_transparency_index) {
@@ -2160,6 +2174,8 @@ PSDInput::indexed_to_rgb(span<unsigned char> dst, cspan<unsigned char> src,
             }
         }
     } else {
+        if (dst.size() < span_size_t(width) * 3)
+            return false;
         for (int i = 0; i < width; ++i) {
             int index      = src[i];
             dst[3 * i + 0] = table[index];        // R

testsuite/psd-colormodes/ref/out.txt

@@ -18,6 +18,11 @@ Comparing "src/pattern2-8-indexed.psd" and "pattern2-8-indexed.psd.tif"
 PASS
 Comparing "src/cmyk-with-alpha.psd" and "cmyk-with-alpha.psd.tif"
 PASS
+indexed-transparency-0.psd :  200 x  150, 4 channel, uint8 psd
+    SHA-1: 670F7DE109D3A8D1E47A90141F555BAE4513A177
+indexed-transparency-255.psd :  200 x  150, 4 channel, uint8 psd
+    SHA-1: BEF32B02F44B369E39670DC2E2D2D1578B4998AD
+indexed-transparency-256-rejected
 Comparing "pattern2-8-rgb.psd.tif" and "ref/pattern2.tif"
 PASS
 Comparing "pattern2-16-rgb.psd.tif" and "ref/pattern2.tif"

testsuite/psd-colormodes/run.py

@@ -24,4 +24,15 @@
                            printinfo=False, output_filename=outfile)
     outputs += [ outfile ]
 
+command += run_app (pythonbin + " src/make-indexed-transparency-psds.py",
+                    silent=True)
+command += info_command ("indexed-transparency-0.psd", verbose=False,
+                         safematch=True)
+command += info_command ("indexed-transparency-255.psd", verbose=False,
+                         safematch=True)
+command += run_app ("(" + oiio_app("iconvert")
+                    + " indexed-transparency-256.psd "
+                    + "out.null > /dev/null 2>&1 "
+                    + "|| echo indexed-transparency-256-rejected)")
+
 outputs += [ "out.txt" ]

testsuite/psd-colormodes/src/make-indexed-transparency-psds.py

@@ -0,0 +1,69 @@
+#!/usr/bin/env python
+
+# Copyright Contributors to the OpenImageIO project.
+# SPDX-License-Identifier: Apache-2.0
+# https://github.com/AcademySoftwareFoundation/OpenImageIO
+
+import struct
+
+
+BASE = "src/pattern2-8-indexed.psd"
+RESOURCE_TRANSPARENCY_INDEX = 1047
+
+CASES = [
+    ("indexed-transparency-0.psd", 0),
+    ("indexed-transparency-255.psd", 255),
+    ("indexed-transparency-256.psd", 256),
+]
+
+
+def resource_section_bounds(data):
+    offset = 26
+    color_data_length = struct.unpack_from(">I", data, offset)[0]
+    offset += 4 + color_data_length
+    resource_length = struct.unpack_from(">I", data, offset)[0]
+    offset += 4
+    return offset, offset + resource_length
+
+
+def find_transparency_index_resource(data):
+    offset, end = resource_section_bounds(data)
+    while offset < end:
+        if offset + 12 > end:
+            raise RuntimeError("truncated image resource")
+        if data[offset : offset + 4] != b"8BIM":
+            raise RuntimeError("unexpected image resource signature")
+
+        resource_id = struct.unpack_from(">H", data, offset + 4)[0]
+        name_length = data[offset + 6]
+        name_size = 1 + name_length
+        if name_size & 1:
+            name_size += 1
+        data_length_offset = offset + 6 + name_size
+        data_length = struct.unpack_from(">I", data, data_length_offset)[0]
+        data_offset = data_length_offset + 4
+
+        if data_offset + data_length > end:
+            raise RuntimeError("truncated image resource payload")
+        if resource_id == RESOURCE_TRANSPARENCY_INDEX:
+            if data_length != 2:
+                raise RuntimeError("unexpected transparency-index length")
+            return data_offset
+
+        offset = data_offset + data_length
+        if data_length & 1:
+            offset += 1
+
+    raise RuntimeError("transparency-index resource not found")
+
+
+with open(BASE, "rb") as input_file:
+    base_data = input_file.read()
+
+index_offset = find_transparency_index_resource(base_data)
+
+for filename, transparency_index in CASES:
+    data = bytearray(base_data)
+    struct.pack_into(">H", data, index_offset, transparency_index)
+    with open(filename, "wb") as output_file:
+        output_file.write(data)